The World Health Organization predicts the number of people suffering from some form of neurodegenerative disorder to approach 29 million by the year 2020. Such neurodegenerative disorders include Parkinson's disease (PD), Huntington's disease (HD), Alzheimer's disease (AD), vascular dementia, and other disorders. While the etiology of theses disorders varies, the end result is the loss of neurons, which leads to cognitive and/or motor skill dysfunction, and eventually death.
Current treatments to improve the quality of life for afflicted individuals involve the administration of dopamine agonists or L-dopa. However, protracted administration of these drugs leads to decreased response and decreased treatment efficacy. While infusion of trophic factors, such as glial cell line-derived neurotrophic factor (GDNF), has been proposed for treating and/or modulating the progression of neurodegenerarative disorders, it has yet to provide clinical benefits to patients.
The transplantation of healthy cells into tissues of the nigrostriatal system has also been proposed to treat PD and other neurodegenerative disorders; however, survival rate of transplanted embryonic tissues is low (e.g., 5-10% for embryonic ventral mesencephalon (VM) tissue) and the grafts have limited capacity to reinnervate the affected tissues, such as the striatum. The transplantation of stem cells faces similar challenges, in addition to difficulties associated with maintaining desired cell phenotypes.
The treatment of neurodegerative disorders and the management of patients suffering from such disorders imposes a high burden on private and public health care systems, caregivers, and family members. Current therapies are unable to effectively prevent the onset of these disorders or arrest their progression. A need clearly exists for effective treatments for neurodegenerative disorders.